Sewing device, workpiece holding jig, and sewing method

ABSTRACT

A sewing device that, when interposing a workpiece-to-be-sewn between a post head and a pressing mechanism and sewing same by penetrating a machine needle therethrough, shapes the workpiece-to-be-sewn in a prescribed shape and sews same, by seating the workpiece-to-be-sewn in a workpiece holding jig having a plurality of seats arranged along a sewing line for the workpiece-to-be-sewn.

TECHNICAL FIELD

The present invention relates to a sewing device, a workpiece holdingjig, and a sewing method for implementing sewing on a skin material.

BACKGROUND ART

Sometimes, in order to create a high-quality feeling in a vehicleinterior of an automobile, a skin material that has been cut or moldedto match a shape of an interior base material such as an instrumentpanel undergoes implementation of stitch pattern sewing (is providedwith a seam). The sewing has conventionally been performed by a workerusing a fixed type sewing machine. In the sewing machine, aworkpiece-to-be-sewn is disposed on a sewing machine table, and sewingis performed by a sewing machine needle through which a thread has beenpassed being caused to penetrate through and withdraw from thatworkpiece-to-be-sewn.

When performing such sewing, sometimes too, in order to preventdeformation, the sewing is performed with the workpiece-to-be-sewn fixedby a jig of a certain shape. For example, Japanese Laid-Open PatentPublication No. 2017-071382 relates to a method of forming a stitchpattern by a needle thread alone, and describes the workpiece-to-be-sewnbeing supported by a receiving jig. Moreover, Japanese Laid-Open PatentPublication No. 2017-197163 and Japanese Patent No. 6151117 describesewing being performed while the workpiece-to-be-sewn is being pressedpinched between a pressing mechanism and a receiving jig.

SUMMARY OF INVENTION

However, in a conventional sewing device, which is for sewing acomparatively flat portion of the workpiece-to-be-sewn, it is difficultfor the receiving jig to be disposed on a narrow portion curved with asmall radius of curvature like a portion curved at an acute angle, forexample. Therefore, there is a problem that a workpiece-to-be-sewn whichhas been shaped having a curved portion cannot be accurately sewn.

Hence, there is desired a sewing device, a workpiece holding jig, and asewing method that enable sewing to be accurately performed even on aworkpiece-to-be-sewn in a shaped state.

A sewing device according to an aspect of the present invention is asewing device for performing sewing along a certain sewing line on aworkpiece-to-be-sewn in a state of the workpiece-to-be-sewn having beenshaped in a certain shape, the sewing device comprising: a sewingmechanism including: a sewing machine needle configured to, by moving ina reciprocating manner, penetrate through or withdraw from theworkpiece-to-be-sewn; a post bed that faces the sewing machine needleacross the workpiece-to-be-sewn; and a pressing mechanism configured topress the workpiece-to-be-sewn against the post bed from a side of thesewing machine needle; a drive mechanism configured to move the sewingmechanism; and a workpiece holding jig configured to hold theworkpiece-to-be-sewn, wherein the workpiece holding jig includes: aplurality of seating portions disposed in a moving direction of thesewing mechanism, each of the seating portions being configured to holdthe workpiece-to-be-sewn shaped in a certain shape by theworkpiece-to-be-sewn being seated on a seating surface of a certainshape; and a retraction mechanism configured to, according to a positionof the sewing mechanism, retract at least one of the seating portionsfrom the workpiece-to-be-sewn in such a manner that interference betweenthe sewing mechanism and the seating portion is avoided.

According to the above-described sewing device, the workpiece-to-be-sewnis held by the workpiece holding jig including the seating portions eachholding the workpiece-to-be-sewn shaped by being seated on the seatingsurface of the certain shape. As a result, the shapedworkpiece-to-be-sewn can be certainly held, and sewing can be performedby the sewing mechanism even on a portion curved at an acute angle, forexample, without there being any positional misalignment. Moreover, byproviding a retraction mechanism that retracts the seating portion in aregion where there is interference with the sewing mechanism, the sewingmechanism can be moved along the sewing line without there beinginterference with the seating portion.

In the above-described sewing device, in a retraction region where bothsurfaces of the workpiece-to-be-sewn have been set adrift due toretraction of the seating portion, sewing may be performed with thesewing mechanism pinching the workpiece-to-be-sewn to adjust the surfaceof the workpiece-to-be-sewn to a flat surface.

According to the above-described configuration, the workpiece-to-be-sewnis held by the workpiece holding jig including the seating portions eachholding the workpiece-to-be-sewn shaped by being seated on the seatingsurface of the certain shape, and a portion where some of those seatingportions have been retracted is sewn pinched by the sewing mechanism.Thus, a local portion between the pressing portion and the post bed ofthe sewing device can be flattened, and an optimal posture of theworkpiece-to-be-sewn can be obtained, while the shape that has beenshaped is maintained for adjacent portions. As a result, even a portioncurved at an acute angle, for example, can be accurately sewn withoutbeing affected by its shape.

In the above-described sewing device, the sewing device may comprise aplurality of suction holes provided in the seating surface of theseating portion, and the workpiece-to-be-sewn may be held by beingsucked through the suction holes.

According to the above-described configuration, the workpiece-to-be-sewncan be seated on the seating surface of the seating portion by beingsucked. Moreover, by suction being stopped, the workpiece-to-be-sewn canbe released, and a retraction operation can be quickly performed.

In the above-described sewing device, the sewing device may furthercomprise a second workpiece holding jig disposed in a position notinterfering with the moving direction of the sewing mechanism, andconfigured to support the workpiece-to-be-sewn.

According to the above-described configuration, the workpiece-to-be-sewncan be more certainly held, and can be accurately sewn.

In the above-described sewing device, the retraction mechanism isconfigured by a cylinder or cam mechanism.

According to the above-described configuration, the retraction mechanismcan be configured by a simple device configuration, and a deviceconfiguration of the sewing device can be simplified.

Moreover, a workpiece holding jig of another aspect of the presentinvention is a workpiece holding jig used in a sewing device thatincludes a sewing mechanism and a drive mechanism configured to move thesewing mechanism, the sewing mechanism including: a sewing machineneedle configured to, by moving in a reciprocating manner, penetratethrough or withdraw from a workpiece-to-be-sewn; a post bed that facesthe sewing machine needle across the workpiece-to-be-sewn; and apressing mechanism configured to press the workpiece-to-be-sewn againstthe post bed from a side of the sewing machine needle, the workpieceholding jig comprising: a plurality of seating portions disposed in amoving direction of the sewing mechanism, each of the seating portionsbeing configured to hold the workpiece-to-be-sewn maintained in acertain shape by the workpiece-to-be-sewn being seated on a seatingsurface of a certain shape; and a retraction mechanism configured to,according to a position of the sewing mechanism, retract at least one ofthe seating portions from the workpiece-to-be-sewn in such a manner thatinterference between the sewing mechanism and the seating portion isavoided.

Moreover, a sewing method of yet another aspect of the present inventionis a sewing method for performing sewing along a certain sewing line ona workpiece-to-be-sewn in a state of the workpiece-to-be-sewn havingbeen shaped in a certain shape, the sewing being performed using asewing mechanism including: a sewing machine needle configured to, bymoving in a reciprocating manner, penetrate through or withdraw from theworkpiece-to-be-sewn; a post bed that faces the sewing machine needleacross the workpiece-to-be-sewn; and a pressing mechanism configured topress the workpiece-to-be-sewn against the post bed from a side of thesewing machine needle, the sewing method comprising: a step of shapingthe workpiece-to-be-sewn in a certain shape by the workpiece-to-be-sewnbeing seated on a plurality of seating portions disposed along a sewingline of the workpiece-to-be-sewn; a step of forming a retraction regionwhere both surfaces of the workpiece-to-be-sewn have been set adrift byretracting some of the seating portions; and a step of performing sewingwith the both surfaces of the workpiece-to-be-sewn being pinched by thesewing mechanism, in the retraction region of the workpiece-to-be-sewn.

According to the above-described sewing device, workpiece holding jig,and sewing method, sewing can be accurately performed on theworkpiece-to-be-sewn.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a sewing device accordingto a first embodiment of the present invention;

FIG. 2 is a side view of a workpiece holding jig of FIG. 1;

FIG. 3A is a front view of immediately before retraction of a firstseating portion of the workpiece holding jig of FIG. 1, and FIG. 3B is afront view showing a state where the first seating portion hasretracted;

FIG. 4 is a front view of a state where a second seating portion of theworkpiece holding jig has retracted;

FIG. 5 is an enlarged perspective view of a sewing portion of the sewingdevice of FIG. 1;

FIG. 6 is an enlarged perspective view showing dispositions of aworkpiece-to-be-sewn and a seating portion thereof according to a secondembodiment of the present invention;

FIG. 7A is a cross-sectional view showing a cross section taken alongthe line VIIA-VIIA of FIG. 6, along with an enlarged view of partthereof, and FIG. 7B is a cross-sectional view taken along the lineVIIB-VIIB of FIG. 6; and

FIGS. 8A to 8C are schematic views showing a retraction mechanismaccording to a third embodiment, along with operation thereof.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will be presented anddescribed in detail below with reference to the accompanying drawings.Note that “up”, “down”, “left”, and “right” in the description belowrespectively correspond to upward, downward, leftward, and rightward inthe drawings. However, this is an indication of directions which hasbeen adopted for convenience in order to facilitate understanding, anddoes not define directions when a sewing device, a workpiece holdingjig, and a sewing method are actually used.

First Embodiment

As shown in FIG. 1, a sewing device 10 according to the presentembodiment includes: a workpiece holding jig 12; a sewing mechanism 14;and a conveyor robot 16 as a drive mechanism for conveying the sewingmechanism 14. The sewing mechanism 14 is fitted to a tip arm 18 of theconveyor robot 16.

As shown in FIG. 2, the workpiece holding jig 12 comprises a seatingportion 20, a guide pin 22, an air cylinder 24, a vacuum generator 40,and a frame body 26. The seating portion 20 has a seating surface 20 aformed in its upper portion. The seating surface 20 a is formed in thesame shape as a workpiece-to-be-sewn 58 (refer to FIG. 3A), in order forshape of the workpiece-to-be-sewn 58 to be maintained. Note that in theexample illustrated, the seating surface 20 a includes in its uppermostportion a portion which is curved at an acute angle. That seatingsurface 20 a has a plurality of suction holes 30 formed therein. Thesesuctions holes 30 communicate with a negative pressure passage 32 on aninside of the seating portion 20, and that negative pressure passage 32communicates with an air hose 36 a connected to a lower end portion ofthe seating portion 20. This seating portion 20 is supported by theguide pin 22 via a supporting member 22 a.

The guide pin 22 is fitted to the frame body 26 via a guide bush 42.Moreover, a lower end portion of the guide pin 22 is connected to apiston rod 24 a of the air cylinder 24. The guide pin 22 is configuredcapable of moving in an up-down direction integrally with the piston rod24 a while being guided by the guide bush 42.

The air cylinder 24 has its lower end portion fixed to a base portion 28of the frame body 26, has its upper end portion (its end portion on thepiston rod 24 a side) upwardly disposed, and has its piston rod 24 aconfigured capable of moving in an up-down direction of the drawing.This air cylinder 24 is connected with an air hose 44 a and an air hose44 b, and operates by supply of compressed air from an external airsupplying means (not illustrated).

The above-described air cylinder 24 and guide pin 22 configure aretraction mechanism of the seating portion 20, and the seating portion20 is configured retractable in the up-down direction. Note that aretracting direction of the seating portion 20 is not limited to theup-down direction, and there may be movement in a horizontal directionor movement with three-dimensional displacement.

The vacuum generator 40 is fitted to the frame body 26. This vacuumgenerator 40 is supplied with compressed air via air hoses 36 c, 36 dand an electromagnetic valve 39. The vacuum generator 40 is configuredby the likes of a vacuum ejector, for example, and can generate anegative pressure under action of compressed air supplied via theelectromagnetic valve 39. The negative pressure generated by the vacuumgenerator 40 is supplied to an air manifold 38 via an air hose 36 b.

The air manifold 38, as well as including passages that branch on itsinside, comprises valves that control opening/closing of each of thepassages. That air manifold 38 is connected with the air hose 36 a. Asshown in FIG. 1, in the workpiece holding jig 12, a plurality of theseating portions 20 are provided, and a plurality of the air hoses 36 aconnected to these plurality of seating portions 20 are connected to theair manifold 38 of FIG. 2. ON/OFF of suction of the individual seatingportions 20 can be switched with opening/closing of the valves on theinside of the air manifold 38. In the case of there being severalseating portions 20, a plurality of the air manifolds 38 and vacuumgenerators 40 may be provided. Note that a configuration may be adoptedwhereby ON/OFF of suction of the individual seating portions 20 isswitched by the electromagnetic valves 39, instead of by the airmanifold 38. In this case, the air manifold 38 need not be provided withthe valves, and the air manifold 38 functions solely as a branching pathof a passage joining the vacuum generator 40 and the seating portion 20.

Note that instead of the air manifold 38 being connected with the airhoses 36 a from the plurality of seating portions 20, it is alsopossible for each of the seating portions 20 to be individually providedwith the vacuum generator 40.

As shown in FIG. 1, a plurality of the seating portions 20 are disposedalong a sewing direction of the sewing mechanism 14. The seatingsurfaces 20 a of these seating portions 20 are provided along a sewingline where the sewing mechanism 14 performs sewing, and havesubstantially the same shape as a shape of the workpiece-to-be-sewn 58lying along the sewing line (refer to FIG. 5).

The seating portions 20 are each respectively provided with the aircylinder 24 and the guide pin 22, and the individual seating portions 20are configured to be retractable. That is, the seating portions 20 areconfigured to be retractable, in order, with approach of the sewingmechanism 14.

As shown in FIG. 1, the sewing mechanism 14 comprises a main body 50formed in a U shape when viewed from the side, and projections 50 a, 50b facing each other of that main body 50 are provided with a post bed46, a pressing mechanism 48, and a sewing machine needle 49. As shownenlarged in FIG. 5, the pressing mechanism 48 and the sewing machineneedle 49 are provided on a side of one of the projections, that is, theprojection 50 a, and extend out toward the other of the projections,that is, the projection 50 b. The post bed 46 is provided on a side ofthe other projection 50 b, and extends out toward the pressing mechanism48 and the sewing machine needle 49.

The pressing mechanism 48 is configured projectable toward the post bed46 via a shaft 48 a, and is configured in such a manner that, whensewing is performed on the workpiece-to-be-sewn 58, the pressingmechanism 48 presses the workpiece-to-be-sewn 58 against a tip of thepost bed 46. A tip of the pressing mechanism 48 is provided with a pairof through-holes 48 b allowing insertion therethrough of a tip of thesewing machine needle 49.

The sewing machine needle 49 is fitted so as to be enabled to move in areciprocating manner in the up-down direction by a drive mechanism (notunillustrated) of the projection 50 a. Reciprocating movement of thesewing machine needle 49 describes an elliptical locus when viewed froma front of the main body 50. This results in it being configured suchthat even when the main body 50 is moved at a constant speed, the sewingmachine needle 49 is penetrated through the workpiece-to-be-sewn 58while maintaining a constant position with respect to theworkpiece-to-be-sewn 58. The tip of this sewing machine needle 49 has athread 52 inserted therethrough, and is inserted into a receivingportion of the post bed 46 via the through-hole 48 b. Although thesewing machine needle 49 is not specifically limited, two items of thesewing machine needle 49 are illustrated, and these can form twoparallel stitch patterns S.

The post bed 46 is provided with an unillustrated looper that holds aloop portion of the thread 52 formed by penetration of the sewingmachine needle 49. That post bed 46 catches the loop portion of thesewing machine needle 49 on the next loop portion formed by apenetrating portion of the sewing machine needle 49 to connect up theloop portions, whereby sewing is performed.

The conveyor robot 16 proceeds to convey the sewing mechanism 14 andmove a sewing portion of the sewing mechanism 14 along the sewing lineat a constant speed. The conveyor robot 16 inclines the main body 50 inaccordance with a shape of a sewing position of the workpiece-to-be-sewn58, and thereby disposes the sewing machine needle 49 at an inclinationperpendicular to the sewing position of the workpiece-to-be-sewn 58.

In the above configuration, the workpiece holding jig 12, the sewingmechanism 14, and the conveyor robot 16 operate under control action ofan unillustrated control circuit. The sewing device 10 according to thepresent embodiment is basically configured as above. Operationaladvantages thereof, along with operation of the sewing device 10, willbe described below.

As shown in FIG. 3A, the workpiece-to-be-sewn 58 is placed on top of theworkpiece holding jig 12. The workpiece-to-be-sewn 58 is held by theworkpiece holding jig 12 in a state of being seated on the seatingsurface 20 a by being sucked through the suction holes 30 of the seatingportion 20. In the case of the workpiece-to-be-sewn 58 used in aninterior material of a vehicle, the strength thereof is comparativelyhigh, hence even if a back surface of the workpiece-to-be-sewn 58 ispartially seated on the seating portion 20, without the entire backsurface being seated thereon, posture can be maintained to a certainextent. In this case, a portion where the seating portion 20 has beenretracted can be elastically deformed to a certain degree with respectto pinching by the sewing mechanism 14.

Immediately after the workpiece-to-be-sewn 58 has been placed on theworkpiece holding jig 12, sewing is started in a state of theworkpiece-to-be-sewn 58 being sucked by all of the seating portions 20.Subsequently, an end portion of the workpiece-to-be-sewn 58 is pinchedby the pressing mechanism 48 and the post bed 46 of the sewing mechanism14, and sewing is performed while penetrating and withdrawing the sewingmachine needle 49 through/from the workpiece-to-be-sewn 58.

As shown in FIG. 5, the post bed 46 is arranged separated in a verticaldirection from the back surface of the workpiece-to-be-sewn 58 in orderto prevent interference with the workpiece-to-be-sewn 58. In the case ofthe present embodiment, it may be separated by about 5 mm to 10 mm, forexample. As a result, the shape of the workpiece-to-be-sewn 58 shaped bythe seating portion 20 can be prevented from being deformed by the postbed 46, and positional misalignment of the sewing line can be prevented.The pressing mechanism 48 pushes the workpiece-to-be-sewn 58 to aposition of a tip surface of the post bed 46, whereby the pressingmechanism 48 forms a flat surface on a surface of theworkpiece-to-be-sewn 58 at a portion between the post bed 46 and thepressing mechanism 48, and adjusts an inclination of the flat surface tobe substantially perpendicular to the sewing machine needle 49.

The sewing mechanism 14 moves at a constant speed in a rightwarddirection in the drawings, by means of the conveyor robot 16.Accordingly, as shown in FIG. 3B, the first seating portion 20 at aposition interfering with the sewing mechanism 14 is retracted. When theseating portion 20 is retracted, supply of negative pressure to theseating portion 20 is stopped, thereby releasing suction of theworkpiece-to-be-sewn 58. Then, by the air cylinder 24 being lowered, theseating portion 20 is retracted to a position not interfering with thesewing mechanism 14.

As a result, the workpiece-to-be-sewn 58 attains a state where bothsurfaces thereof have been set adrift from the seating portion 20, andin that portion, the sewing mechanism 14 can be moved along the sewingline. Note that even when the first seating portion 20 has beenretracted, the shape of the workpiece-to-be-sewn 58 is maintained by thesecond seating portion 20, hence sewing can be performed in a statewhere the workpiece-to-be-sewn 58 has been shaped.

Depending on the inclination of the surface at the sewing position ofthe workpiece-to-be-sewn 58, the sewing mechanism 14 may be obliquelyinclined. In that case, a plurality of the seating portions 20 in arange interfering with the sewing mechanism 14 should be retracted.

Next, as shown in FIG. 4, the second seating portion 20 is retracted inaccordance with movement of the sewing mechanism 14. Moreover, theseating portion 20 that has been passed by the sewing mechanism 14 isreturned to its original position.

As described above, the seating portion 20 that interferes with thesewing mechanism 14 is retracted in accordance with movement of thatsewing mechanism 14, whereby it can be prevented that the seatingportion 20 interferes with the sewing mechanism 14. As a result, sewingcan be performed by the sewing mechanism 14 while maintaining a state ofthe workpiece-to-be-sewn 58 having been shaped by the seating portion20.

Second Embodiment

In the present embodiment, an example where sewing of the stitch patternS is implemented assuming an interior material configuring an instrumentpanel of a vehicle to be a workpiece-to-be-sewn 68, will be described.Note that a configuration of the sewing device 10 used in the presentembodiment is basically similar to that shown in FIG. 1, and adescription thereof will be omitted.

As shown in FIG. 6, the workpiece-to-be-sewn 68 is supplied in a stateof having been shaped in a shape of the instrument panel. As shown inthe enlarged portion of FIG. 7A, this workpiece-to-be-sewn 68 isconfigured from: a base material 68 b constituted by a hard syntheticresin, that is formed in a required shape; and a skin material 68 a thatis soft, and is adhered to a surface of the base material 68 b. The basematerial 68 b is constituted by extrusion-molded polypropylene, forexample, and the skin material 68 a is constituted by a soft elastomermaterial that has been applied with a leather-like pattern, for example.

As shown in FIG. 6, a curve L of the workpiece-to-be-sewn 68 is a sewingline where sewing is performed, and the stitch pattern S is formed alongthis sewing line L. In the present embodiment, a plurality of theseating portions 20 are provided along the sewing line L. The seatingsurface 20 a of the seating portion 20 is configured with substantiallythe same shape as the workpiece-to-be-sewn 68, and is provided with thesuction holes 30 (refer to FIG. 1). Each of the seating portions 20 isprovided with a retraction mechanism (not illustrated) that retracts theseating portion 20 in the Z direction of FIG. 6. A configuration of thisretraction mechanism is similar to that described with reference to FIG.2.

The sewing mechanism 14 (refer to FIG. 1) proceeds to move along thesewing line L of the workpiece-to-be-sewn 68. By the seating portions 20of portions interfering with the sewing mechanism 14 proceeding to beretracted with movement of the sewing mechanism 14, sewing can beperformed while shape distortion and positional misalignment of theworkpiece-to-be-sewn 68 are prevented. Moreover, a configuration may beadopted whereby the workpiece-to-be-sewn 68 is supported making combineduse of a fixed type workpiece holding jig 60 (a second workpiece holdingjig) that does not include the retraction mechanism, for a portionseparated from the sewing line L where there is no risk of there beinginterference with the sewing mechanism 14.

Moreover, the conveyor robot 16 (refer to FIG. 1) detects an inclinationof a surface of a sewing portion of the workpiece-to-be-sewn 68, andcontrols an inclination of the sewing mechanism 14 so that the sewingmachine needle 49 of the sewing mechanism 14 is perpendicular to thesurface of the sewing portion. That is, as shown in the enlargedperspective view of FIG. 6, the sewing device 10 (refer to FIG. 1)detects two tangents B, C that are orthogonal at a portion between thetwo sewing machine needles 49, and finds a direction of a perpendicularline D to those tangents B, C. Then, the sewing device 10 controls theinclination of the sewing mechanism 14 so that an axial direction of thesewing machine needle 49 coincides with the perpendicular line D. Notethat when the shape of the workpiece-to-be-sewn 68 is fixed, there is noneed for the inclination of its surface to be detected by the conveyorrobot 16 on each occasion of sewing. In this case, a configuration maybe adopted whereby the conveyor robot 16 moves according to a teachingoperation that is input in advance.

For example, in the cross section taken along the line VIIA-VIIA of FIG.6, the inclination of the perpendicular line D at the sewing position isgreatly inclined in a horizontal direction, as shown in FIG. 7A. Insewing of this portion, a plurality of the seating portions 20 that mayinterfere with the sewing mechanism 14 are retracted.

Note that for a portion curved at an acute angle as shown in FIG. 7B,the shape of the workpiece-to-be-sewn 68 cannot be maintained by thefixed type workpiece holding jig 60 alone. Therefore, in a conventionalsewing device, tilting where the workpiece-to-be-sewn 68 inclines toleft and right of the drawing ends up occurring when the pressingmechanism 48 is pressed against the post bed 46 of the sewing mechanism14, and sewing cannot be accurately performed. In contrast, according tothe present embodiment, the shape of the workpiece-to-be-sewn 68 can bemaintained by the seating portions 20 on both sides, that is, afrontward side and a rearward side in the moving direction of the sewingmechanism 14, hence sewing can be accurately performed even on a portioncurved at an acute angle.

Third Embodiment

In the present embodiment, an example where a cam mechanism 70 has beenadopted for the retraction mechanism of the workpiece holding jig 12(refer to FIGS. 1 and 2), will be described. As shown in FIG. 8A, in thepresent embodiment, the cam mechanism 70 is provided under the guide pin22.

The cam mechanism 70 of the present embodiment comprises: a roller 72;and a sliding portion 76 that abuts on that roller 72. The roller 72 issupported by a shaft portion 72 a to rotate in an arrow direction of thedrawing by that shaft portion 72 a. A recess 74 receding in an axialdirection is formed in the roller 72. The sliding portion 76 isconnected to a base end portion of the guide pin 22. This slidingportion 76 is configured to slide along an outer peripheral portion ofthe roller 72.

As shown in FIG. 8B, the sliding portion 76 moves downwardly withpassage of the recess 74 of the sliding portion 76, and, accordingly,the guide pin 22 and the seating portion 20 connected to an upper endthereof descend. As a result, a retraction operation of the seatingportion 20 can be performed.

Moreover, as shown in FIG. 8C, by the sliding portion 76 coming out ofthe recess 74 with rotation of the roller 72, the guide pin 22 rises,and the seating portion 20 returns to its original position. Theworkpiece holding jig 12 (refer to FIG. 1) can be realized by aplurality of such cam mechanisms 70 being disposed in the movingdirection of the sewing mechanism 14. In this case, by staggering phasesof the rollers 72 of the cam mechanisms 70, there can be realized aretraction mechanism that retracts the seating portions 20 insynchronization with movement of the sewing mechanism 14. Thus,according to the present embodiment, a device configuration of theworkpiece holding jig including the retraction mechanism can besimplified.

In the above description, the present invention has been described bypresenting preferred embodiments thereof. However, the present inventionis not limited to the above-described embodiments, and it goes withoutsaying that various modifications thereof are possible in a range notdeparting from the spirit of the present invention.

What is claim is:
 1. A sewing device for performing sewing along acertain sewing line on a workpiece-to-be-sewn in a state of theworkpiece-to-be-sewn having been shaped in a certain shape, the sewingdevice comprising: a sewing mechanism including: a sewing machine needleconfigured to, by moving in a reciprocating manner, penetrate through orwithdraw from the workpiece-to-be-sewn; a post bed that faces the sewingmachine needle across the workpiece-to-be-sewn; and a pressing mechanismconfigured to press the workpiece-to-be-sewn against the post bed from aside of the sewing machine needle; a drive mechanism configured to movethe sewing mechanism; and a workpiece holding jig configured to hold theworkpiece-to-be-sewn, wherein the workpiece holding jig includes: aplurality of seating portions disposed in a moving direction of thesewing mechanism, each of the seating portions being configured to holdthe workpiece-to-be-sewn shaped in a certain shape by theworkpiece-to-be-sewn being seated on a seating surface of a certainshape; and a retraction mechanism configured to, according to a positionof the sewing mechanism, retract at least one of the seating portionsfrom the workpiece-to-be-sewn in such a manner that interference betweenthe sewing mechanism and the seating portion is avoided.
 2. The sewingdevice according to claim 1, wherein in a retraction region where bothsurfaces of the workpiece-to-be-sewn have been set adrift due toretraction of the seating portion, sewing is performed with the sewingmechanism pinching the workpiece-to-be-sewn to adjust the surface of theworkpiece-to-be-sewn to a flat surface.
 3. The sewing device accordingto claim 1, comprising a plurality of suction holes provided in theseating surface of the seating portion, wherein the workpiece-to-be-sewnis held by being sucked through the suction holes.
 4. The sewing deviceaccording to claim 1, further comprising a second workpiece holding jigdisposed in a position not interfering with the moving direction of thesewing mechanism, and configured to support the workpiece-to-be-sewn. 5.The sewing device according to claim 1, wherein the retraction mechanismis configured by a cylinder or cam mechanism.
 6. A workpiece holding jigused in a sewing device that includes a sewing mechanism and a drivemechanism configured to move the sewing mechanism, the sewing mechanismincluding: a sewing machine needle configured to, by moving in areciprocating manner, penetrate through or withdraw from aworkpiece-to-be-sewn; a post bed that faces the sewing machine needleacross the workpiece-to-be-sewn; and a pressing mechanism configured topress the workpiece-to-be-sewn against the post bed from a side of thesewing machine needle, the workpiece holding jig comprising: a pluralityof seating portions disposed in a moving direction of the sewingmechanism, each of the seating portions being configured to hold theworkpiece-to-be-sewn maintained in a certain shape by theworkpiece-to-be-sewn being seated on a seating surface of a certainshape; and a retraction mechanism configured to, according to a positionof the sewing mechanism, retract at least one of the seating portionsfrom the workpiece-to-be-sewn in such a manner that interference betweenthe sewing mechanism and the seating portion is avoided.
 7. A sewingmethod for performing sewing along a certain sewing line on aworkpiece-to-be-sewn in a state of the workpiece-to-be-sewn having beenshaped in a certain shape, the sewing being performed using a sewingmechanism including: a sewing machine needle configured to, by moving ina reciprocating manner, penetrate through or withdraw from theworkpiece-to-be-sewn; a post bed that faces the sewing machine needleacross the workpiece-to-be-sewn; and a pressing mechanism configured topress the workpiece-to-be-sewn against the post bed from a side of thesewing machine needle, the sewing method comprising: a step of shapingthe workpiece-to-be-sewn in a certain shape by the workpiece-to-be-sewnbeing seated on a plurality of seating portions disposed along a sewingline of the workpiece-to-be-sewn; a step of forming a retraction regionwhere both surfaces of the workpiece-to-be-sewn have been set adrift byretracting some of the seating portions; and a step of performing sewingwith the both surfaces of the workpiece-to-be-sewn being pinched by thesewing mechanism, in the retraction region of the workpiece-to-be-sewn.